Inside a tooth, there is tissue called dental pulp, and this dental pulp is composed of nerves, blood vessels, and so on, and supplies nourishment, water, and the like to the tooth, and performs a sensory function. An inflammation of the dental pulp caused by an infection resulting from dental caries and so on is called pulpitis, and causes an inflammation of periapical bone tissue of the root portion of the tooth.
In this case, root canal treatment (endodontic treatment) may be performed. The root canal treatment is a procedure of completely removing the infected dental pulp tissue with a special tool, and disinfecting the root canal, thereby making the root canal germ-free, and filling the space previously occupied by the dental pulp with a biocompatible material.
In order to treat the root canal, a step of measuring the length of the root canal should be performed in advance.
Root canal length measuring devices which are usable to measure the length of the root canal are devices using electrical resistances of human body to detect that the devices reach periapical tissue, and have been created on the basis of a principle in which if a lip and periapical periodontal ligament of a person are connected by a conducting wire, and a cutting tool such as a file or a reamer is inserted into a root canal while a current having predetermined intensity is applied, when the cutting tool reaches the apex of a root of a tooth, resistance becomes a certain value.
Most root canal length measuring devices using the above-described method to measure the lengths of root canals are provided in a terminal form, and are placed on tables of unit chairs or separate tables installed in dental offices, and then are used to measure the lengths of root canals.
For this reason, as treatments progress, lead wires connected to probes increase inconvenience, and when users (dentists) provide treatments, they should check small-sized display units (LCDs) of those root canal length measuring devices while observing affected parts of patients, and thus feel inconvenience.